The present disclosure relates to antibodies capable of selectively binding to various domains on the chains of laminin-332, compositions thereof, and methods of using such antibodies/compositions for various purposes.
Laminins are trimeric basement membrane (BM) glycoproteins with roles in cell adhesion, proliferation, migration and differentiation. The laminin molecule is a cross-shaped heterotrimer consisting of one heavy chain (alpha) and two light chains (beta and gamma). The three chains are associated through a carboxyl terminal coiled coil domain. In addition, all of the alpha chains have a large globular G domain at the carboxyl terminus.
In mammals, five genetically distinct alpha (α), three beta (β), and three gamma (γ) chains can form at least 14 different combinations of these chains (References 1, 2). Laminin-332 (also denoted as LN-332, also known as laminin-5, LN-5, kalinin, nicein) has a chain composition α3:β3:γ2 (FIG. 8) and is essential for anchorage of epithelial cells and specifically found in epithelial BMs (References 3-5). LN-332 defects lead to detachment of epithelia and the fatal skin blistering disease junctional epidermolysis bullosa (References 6-8). LN-332 also has a role in proliferation and locomotion of epithelial cells, such as in keratinocytes of healing wounds (References 9, 10). The globular domain (G-domain) of the α3 chain binds to the cell surface through integrin receptors α6β4 and α3β1 (Reference 11) and evokes anti-apoptotic signals through focal adhesion kinase (References 12, 13), while the short arms of the β3 and γ2 chains bind to type VII collagen in the stroma (Reference 14).
LN-332 is up-regulated in various epithelial cancers, including colon, gastric, mammary duct and squamous cell carcinomas, as well as melanomas (References 5-18), but not in mesenchymal cancers (References 15, 16). High expression of the γ2 chain of LN-332 has been found to correlate with poor prognosis of cervical squamous cell carcinomas (Reference 19). LN-332 is also a major scattering factor stimulating invasive and metastatic capacity of several tumor cell lines in vitro (References 20, 21). In the cancer tissue, the protein is primarily expressed at the invasive front, as well as in micro-metastases. Down-regulation of LN-332 has been reported in epithelial prostate cancer (Reference 22) and also in breast cancers (Reference 23).
LN-332 expression has been associated with tumorigenesis. Thus, when HT1080 tumor cells constitutively expressing laminin β3 and γ2 chains but not α3 were transfected with laminin α3 cDNA the cells grew significantly larger tumors in nude mice than untransformed cells (Reference 24). Moreover, LN-332 negative (as well as α4 integrin negative) keratinocytes did not become tumorigenic upon transfection with ras-IκBα in contrast to normal keratinocytes (Reference 25).
Since most cancers are of epithelial origin and positive for LN-332 expression, present applicants investigated whether this protein has a general role for the adhesion and migration process of invading carcinoma cells, and if interference with those functions might influence tumor growth and spread. In particular, present applicants studied the role of LN-332 for carcinoma cell adhesion and migration in vitro and demonstrated that interference with the binding of this protein to the cells inhibits these functions and induces apoptosis. Furthermore, present applicants showed that antibodies against the cell and matrix binding domains of LN-332 target to several types of carcinomas growing in vivo and effectively inhibit tumor growth and metastasis in mice.